Glucose sensor response

Entrapment of biochemically reactive molecules into conductive polymer substrates is being used to develop electrochemical biosensors (212). This has proven especially useful for the incorporation of enzymes that retain their specific chemical reactivity. Electropolymerization of pyrrole in an aqueous solution containing glucose oxidase (GO) leads to a polypyrrole in which the GO enzyme is co-deposited with the polymer. These polymer-entrapped GO electrodes have been used as glucose sensors. A direct relationship is seen between the electrode response and the glucose concentration in the solution which was analyzed with a typical measurement taking between 20 to 40 s. 

C. Malitesta, F. Palmisano, L. Torsi, and P. Zambonin, Glucose fast-response amperometric sensor based on glucose oxidase immobilized in an electropolymerized poly(o-phenylenediamine) film. Anal. Chem. 

FIGURE 11.30 Zn Nanowire glucose sensor (a) glucose oxidase impregnated Zn nanowire electrode (b) amperimetric response of different glucose concentration. 

Figure 7. Amperometric response of glucose sensors prepared using LB film-coated electrodes. ( ) multilayer GOx (o) monolayer GOx sensors.

Fig. 2.16 Theoretical (full points) and experimental (open points) time response curve for glucose sensors to step change in concentration (from 0 to 1 mM) (adapted from Caras et al., 1985b, p. 1922)...

Figure 4. Apparatus for in vitro measurement of dynamic response properties of the subcutaneous type glucose sensor...

Glucose sensors II and HI were prepared from the semipermeable membrane of PMSP, poly(1-trimethylsilyl-l-propyne), which has 4 times the oxygen permeability compared with that of FEP membrane. The response properties of sensor H, using a PMSP membrane with 25 Um diameter pinhole, were almost similer to that of the sensor I, so that their calibration curves were not presented in this paper. 

Figure 5. Dynamic response curves of glucose sensor I under various oxygen tensions (%)...

Table 1 Linear response range and response time of glucose sensors with various glucose semipermeable membranes...

In vivo tests. The response properties of the glucose sensors I to IV are summarized in Table 1. The sensor HI and W have more desirable responses than the sensor I and H as a glucose sensor for the artificial pancreas. In the present paper, however, the results of in vivo tests obtained by using the sensor I will be demonstrated in the later section. 

Buckingham B, Block J, Burdick J, Kalajian A, Kollman C, Choy M, Wilson DM, Chase P. Response to nocturnal alarms using a real-time glucose sensor. Diabetes Technology and Therapeutics 2005, 7, 440-447. 

Gifford R, Batchelor MM, Lee Y, Gokulrangan G, Meyerhoff ME, Wilson GS. Mediation of in vivo glucose sensor inflammatory response via nitric oxide release. Journal of Biomedical Materials Research Part A 2005, 15A, 755-766. 

Polyurethanes have also been employed as outer sensor membranes. Yu et al. evaluated the biocompatibility and analytical performance of a subcutaneous glucose sensor with an epoxy-enhanced polyurethane outer membrane.15 The membrane was mechanically durable and the resulting sensors were functional for up to 56 days when implanted in the subcutaneous tissue of rats. Despite the improved sensor lifetime, all of the polyurethane-coated sensors were surrounded by a fibrous capsule, indicating an enduring inflammatory response that is undesirable due to the aforementioned effects on analytical sensor performance. To date, the clinical success of most passive approaches has been rather limited. It is doubtful that one passive material alone will be capable of imparting long-term (i.e., weeks to months) biocompatibility for in vivo use due to the extremely dynamic nature of the wound environment. 

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